1. Field of the Invention
The present invention relates to a new type of material that employs diamond to enhance its physical properties. More specifically, the present invention relates to a diamond material coated into and throughout an open-cell reticulated structure that permits fluid flow through its void volume.
2. The Prior Art
There is a broad class of known materials classed as open-cell foams. These materials consist of reticulated structures through which fluids can flow. They resemble the intersections observed in a mass of bubbles, hence their description as xe2x80x9cfoamxe2x80x9d.
These materials can be fabricated by a variety of means, and are available in various ceramics, metals, and carbon. These materials exhibit a three-dimensional reticulated unitary structure, which distinguishes them from other open-cell structures, such as stacked screens, comprising the mechanical juxtaposition of otherwise separate components.
These materials find a variety of uses in industry. For example, foams made of silicon carbide can be used to filter slag from molten aluminum. In other applications, fluid flows through a foam structure to carry away or supply heat. In this use, the inherent high surface area to volume ratio of the foam provides superior heat transport compared to planar heat exchangers.
Diamond/nondiamond composite materials formed by chemical vapor infiltration are also known in the art. Examples of such materials are found in U.S. Pat. Nos. 5,609,955 and 5,614,140. These materials are formed by consolidation of particulate substrate materials with diamond deposited through chemical vapor infiltration processes. These materials often contain residual porosity, or voids, that remain due to the blockage of diffusion channels that supply activated gas species to the interior. These voids degrade the material""s bulk thermal conductivity and can act as stress concentrators to reduce breakage resistance. These residual porosities or voids are often closed off from the external environment and therefore cannot play any role in supporting fluid flow through the consolidated composite material.
These materials are distinct from the present invention in two important respects. First, they are formed by fusion of a multiplicity of separate particles into a single resultant structure, whereas the instant invention coats an existing unitary structure with diamond. Second, diamond composites formed using the teachings found in prior art exhibit little or no permeability to fluid flow through a their volume, whereas a specific object of the instant invention is maintenance of permeability to permit fluid flow through the structure.
The present invention is diamond foam, and means for its manufacture, consisting of diamond deposited on a pre-existing framework, said framework being compatible with diamond deposition, and having an open-cell structure adequate to permit fluid flow in at least one direction (axis) through the material subsequent to diamond deposition, said framework having structural integrity prior to the deposition of diamond. In particular, the framework does not consist of loose particles or fibers consolidated by diamond deposition.
A diamond foam according to the present invention comprises diamond deposited material on a substrate having an open contiguous structure that permits the flow of fluids in at least one direction through the material.
A method for forming a diamond foam according to the present invention comprises providing a foam substrate; preparing the foam substrate for diamond deposition; and depositing diamond material on the foam substrate. According to the present invention, the diamond material can be deposited on the foam substrate by one of several diamond deposition methods.